Devilman : The Birth/Demon Bird (Vol. 1 & 2)

Akira is your typical schoolkid until his childhood best friend Ryo shows up and pulls him into a web of demons and deceit. As Ryo explains, Dante talks about demons frozen in the ice in The Divine Comedy, and now global warming is melting that ice, freeing them. Akira and Ryo decide to team up and save the world. Akira makes a dangerous choice to become a devil in order to defeat the other devils.